The present invention concerns a polyarylene thioether (hereinafter referred to as PATE) of high crystallizing rate and a process for producing the same.
More specifically, the present invention concerns a PATE of high crystallizing rate, having a necessary time for 50% crystallization of not more than 50 seconds from the molten polymer at 250.degree. C., as well as a process for producing such PATE of high crystallizing rate.
PATE has been developed as a heat resistant, chemical resistant and flame resistant thermoplastic resin. Particularly, since PATE crystallizes easily, it has advantageous features in that it is excellent in the melt processability such as for injection molding and in that resultant molding products have excellent physical properties such as dimensional stability, strength, hardness and insulating performance. Taking these advantages, PATE has been employed in the industrial fields of electric, electronics, automobiles, aircrafts, precision instruments and chemicals.
However, since the crystallizing rate of PATE from the molten state is still not sufficiently high upon conducting melt processing, particularly, injection molding, a relatively long period of time is necessary till the molten product in a mold is solidified sufficiently. As a result, there has been a problem that the molding cycle can not be increased.
The present inventors have made an extensive study on a method of shortening the time required for a molten polymer to crystallize from the molten state and, as a result, have found that a novel PATE crystallizable at a high rate can be obtained by treating a PATE of an adequate molecular weight or an adequate inherent solution viscosity .eta..sub.inh with a solution of a non-oxidative strong acid or a strong-acid-weak-base type salt.
The present invention has been attained based on the above finding.